During a meeting attended by fewer than half a dozen members of the public Monday night at Maine Turnpike Authority headquarters on outer Congress Street, a project engineer outlined the repairs needed to bring the 55-year-old bridge spanning the Presumpscot River up to current safety and design standards.

“It’s not going to fall down tomorrow; the turnpike authority is doing a good job of maintaining it,” Bob Driscoll said.

With the last major rehabilitation work on the bridge completed in 1979, Driscoll said the structure is in need of a new deck, railings, bearings, expansion joints, and repairs and expansion of piers and abutments.

As part of the project, the width will be increased by 24 feet in the southbound direction and 22 feet in the northbound direction to bring the shoulder width up to current design standards and to maintain two lanes of traffic in each direction during all phases of construction.

The additional width, Driscoll said, will also allow a longer acceleration lane for merging on-ramp traffic, accommodate a future additional travel lane in each direction and will provide an added buffer to increase drivers’ perception of security.

But to complete this work more safely, faster and at a lower cost, turnpike officials are suggesting closing the northbound on-ramp for the first year of the project. This will allow two lanes in each direction to remain open while bridge widening is completed during the first phase and work on the inside lanes is accomplished during the second phase.

According to estimates, the ramp closure will cut the project’s length by nine months, from 27 months to 18. It will also reduce the cost by $750,000, for a total cost of $7.2 million.

Safety is also driving the recommendation to close the on-ramp. In an alternative plan, one northbound lane of the turnpike would be closed approaching the bridge, slowing oncoming ramp traffic and causing what engineers predict would be multiple rear-end collisions as drivers tried to merge into mainline traffic, often from a stopped position.

About 1,600 vehicles per day use the northbound on-ramp, less than half the volume of the southbound on-ramp.

“We’ve learned from the process of closing roads … we’re typically dealing with commuters and they will find their way,” Driscoll said.

But the few members of the public at Monday’s meeting weren’t happy about having to seek an alternate route.

“With gas the way it is, this is going to bring people way out of their way,” limousine driver Bob Lilley, of South Portland, said.

Lilley suggested building a new bridge instead of repairing the existing one, a process Driscoll said would take only nine months.

Though he said the MTA considered building new, it dismissed the idea because of the complications of working in the river and the logistics of getting the necessary equipment and workers into tight spaces.

Dennis Mason, of Lewiston, asked for “a break” on tolls from the MTA during construction. Mason said he commutes to his job in Falmouth and will now have to go out of his way to get home.

MTA official Conrad Welzel said there have been discussions about a toll reduction for E-ZPass users, but no decision has been made.

The anticipated start of the bridge project is May 2010, with the ramp closed from June 2010 to June 2011 and the project completed by August 2012.

Alternative routes suggested by the MTA include Interstate 295 southbound in Portland to Maine Turnpike Exit 45 northbound in South Portland and Routes 26/100 in West Falmouth to Exit 53 northbound.

The Maine Turnpike Authority plans to close the northbound on-ramp from the Falmouth spur at Exit 52 for a year during reconstruction of a bridge that spans the Presumscot River.Bob Driscoll, of project designer HNTB Corp. of Westbrook, explains the proposal during a public information session Monday at MTA headquarters in Portland.